Github user JoshRosen commented on a diff in the pull request:
https://github.com/apache/spark/pull/6423#discussion_r31370774
--- Diff:
core/src/main/scala/org/apache/spark/storage/ShuffleBlockFetcherIterator.scala
---
@@ -290,22 +287,15 @@ final class ShuffleBlockFetcherIterator(
sendRequest(fetchRequests.dequeue())
}
- val iteratorTry: Try[Iterator[Any]] = result match {
+ val iteratorTry: Try[InputStream] = result match {
case FailureFetchResult(_, e) =>
Failure(e)
case SuccessFetchResult(blockId, _, buf) =>
// There is a chance that createInputStream can fail (e.g.
fetching a local file that does
// not exist, SPARK-4085). In that case, we should propagate the
right exception so
// the scheduler gets a FetchFailedException.
- Try(buf.createInputStream()).map { is0 =>
- val is = blockManager.wrapForCompression(blockId, is0)
- val iter =
serializerInstance.deserializeStream(is).asKeyValueIterator
- CompletionIterator[Any, Iterator[Any]](iter, {
- // Once the iterator is exhausted, release the buffer and set
currentResult to null
- // so we don't release it again in cleanup.
- currentResult = null
- buf.release()
- })
+ Try(buf.createInputStream()).map { inputStream =>
--- End diff --
We might also treat this patch as an opportunity to revisit why we're using
`Try` here. It might be fine to keep `Try` as the return type but I'm not
necessarily convinced that we should be calling `Try.apply()` here since I
think it obscures whether we'll need to perform any cleanup after errors (for
instance, do we need to free `buf`? Is `buf` guaranteed to be non-null or
could this fail with an NPE on the `buf.createInputStream()` call? I feel that
the `Try.apply()` makes it easy to overlook these concerns.
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